Hold-down and chip collecting attachment for drills



' Jan. 18, 1944. y H R, FISCHER A2,339,324

HOLD DOWN AND CHIP COLLECTING ATTACHMENT FCR DRILLS Filed Dec. 9, 1941 N3 sheets-sheet 1 Tli. 36

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.55a \O e Tllzli. l (D INVENTOR Afan/,4K0 -c/EK Jan. 1s, 1944. H. R. FISCHER 2,339,324

HOLD DOWN AND CHIP COLLECTING ATTACHMENT FOR DRIL'LS Filed Dec. 9, 1941 5 Sheets-Sheet 2 y\ s s Ni; ffl/111111111711115',

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mf 'l illiml Inl Jan. 18, 1944. H. R. FISCHER HOLD DOWN AND CHIP COLLECTING ATTACHMENT FOR DRILLS Filed Dec. 9, 1941 y 3 Sheets-Sheet 3 .'.Qatented Jan. 1.8, 1944 UNITED STATES PATENT oFFlcE 'mmm n. Fischer, permit, man., mignonu Chicago Pneumatic Tool Company, New York.

N. Y., a corporation of New Jersey application December, 9, 1941, serai so. 422,200

11 claims. (ci. '1i-55) This invention relates to attachments for drilling and like tools designed to control the disposal of dust particles created by the drill.'

In its broader aspects the invention is similar to that disclosed in Patent .No. 2,246,916, issued June 24, 1941, to H. R. Fischer. Like the device of that patent the present-invention is concerned principally with problems of sheet metal drilling which have been especially troublesome in the aircraft industry. In preparing the metal skin covering of airplanes for riveting, a twist drill is driven through the overlapping portions of a pair of sheets in a seriesof predetermined positions to form the rivet holes. Ii no provision is made for holding the metal sheets flrmly together a projectingY burr is formed on both sheets around the drilled hole. 'I'he sheets thereby are held in an uneven spaced relation, which condition is'maintained and intensiiied throughout continued drilling operations as the chips and cut particles work their way outward between the sheets. The presence of the burrs adds to-the diiilculties entailed in joining the sheets together, while the necessity of first removing the metal particles from between the sheets represents a loss in time and labor.

In the Patent 2,246,916 an attachment, ap-l plicable to the conventional handheld rotary power drill, is disclosed which embodies hold down means acting during drilling to press the outer of the work sheets into contact with the inner sheet, and f urtlier embodies means for generating an air current which. constantly picks and exhausts particles from the region of the drill hole and deposits them in a remote dust receptacle. 'I'he present invention contemplates the performanceof the same functions but provides a devicewhich, when compared with the earlier structure,-is more simple, has fewer parts and may be more easily and rapidly controlled.

To modify and improve upon the device of Patent 2,246,916 in these respects is, therefore, a generalobject of the invention.

A more specic object is to facilitate manual shiftingof the tubular attachment to and from working position. This object is attained through the cooperation of a spring urging the attachment from working position and manually operated linkage for` effecting its retraction. The linkage includes a palm held lever underlying the drill in position to be operated by an opening and closing movement of the operators hand. Since, to simplify positioning of the drill, the attachment is retracted and advanced before starting each new drill hole, the greater ease' of u to its front end an adapter operation aiiorded by the linkage of the'present .v invention results in a general speed-up of the `Another object of the -invention is to improvev the method of entraining, in the current of air passing to the dust receptacle,'those particles thrown outward from the drill by centrifugal force. To accomplish this object, the work engaging end of the tubular attachment is formed with radial grooveswhich constitute constantly open air passages circumferentially spaced around the drill.

Other objects and structural details of the invention will be apparent from the following de scription when read in conjunction with the ac- 'l companying drawings, wherein:

Fig. 1 is a view, in side elevation,of a portable drilling too1` equipped with" an attachment of the invention, showing a part of the dust disposal apparatus in longitudinal section and only a fragment ofthe dust bag; l

Fig. 2 is a view of the assembly of Fig. 1, showing the manner in which the tool is held and operated, the tubular attachment being in this instance retracted from working position;

Fig. 3 is an exploded view. in side elevation, of Y the assembly of Fig. 1;

Fig. 4 is a fragmentary view of the tool, showing the attachment of Fig. 1 in longitudinal secution advanced to working position;

Fig. 5 is a view similar to Fig. 4, showing the attachment in retracted position;

Fig. 6 is a front end view of the attachment o f Fig. 1;

Fig. '1 is a view, in cross section, .taken substantially along the line 1-1 of Fig. 4;

Fig. 8 is a detail view of the linkage provided for manual retraction of the attachment;

Fig. 9 is a front end view of the hold down portion of the attachment, this view being enlarged with respect to the other figures;

Fig. 10 is a view, in longitudinal section, taken substantially along the line Ill-l0 of Fig. 9; and

Fig. 11 is a fragmentary view of the tool having an attachment of modiiied construction mounted thereon, the attachment being shown partly in side elevation and partly in longitudinal section. s

The tool illustrated is one of a kind in common use in the aircraft industry, being especially adapted for hand support and powered for the drilling of light sheet metal such as 'aluminum alloy. Its outer casing includes a motor housing 20 mounted on a handle 2| and having secured 22. The adapter 22 to connect and disconnect the motor and the source of current supply, thereby to start and stop operation of the tool. As shown in Fig. 4, the motor shaft 25 has a pinion 28 thereon meshing with a gear 21 secured to a spindle 2B. The

spindle parallels the motor shaft and is rotatably mounted in bearings 29 and 3i within the adapter v 22. The outer end of spindle 23 projects through and beyond the adapter 22 and has a driving connection with a chuck 32, mounted thereon. The chuck 32 is conventional in form, being provided with a plurality of adjustable fingers 33 adapted to grip the shank of a twist drill 34 and lock it in the chuck for rotation therewith and with the spindle 28. In .the operation ofl the tool, it is held in the hands of the operator, and, after the point of the drill has been located in drilling position, the trigger 24 is actuated to start the motor and thereby effect rotation of the drill. The tool is applied .to the work with a steady pressure causing the drill to` advance through the successive s'heet laminations.

According to the present invention the chuck 32 and drill 34 are surrounded by a tubular attachment 35 the interior of which communicates,

through a hose line 36, with a remote dust bag 31 (Fig. 1). 'I'he outer end of the hose line 36 is connected to the bag 31 by a Venturi tube 38 into which extends a compressed air discharge nozzle 39. By means of a separate hose line 4I air under pressure is supplied to the nozzle 39 and directed thereby through the Venturi tube to the dust bag 31. In this manner a jet device is formed which functions to exhaust the air from the hose line 36 and communicating areas.

The front of attachment 35 being open to atmosphere, a steady stream of air, having its source adjacent the point of the Adan and its terminus in the bag 31. HOWS through the attachment dur; ing operation of the jet device. The dust and chips in the region of the drill hole are entrained in this air curent and carried by it to the dust receptacle. Y

Referring particularly to Figs. 3 and 4, it will be seen that the tubular attachment 35 comprises a sleeve 42 and a, sleeve extension 43, the latter being in the form of a drill guide having a longitudinal bore 40 for the passage of the drill therethrough. The sleeve assembly-is coaxial with the drill and chuck 32 and is mounted on a cylinder 44 set in the adapterl 22. Intermediate its ends the ,cylinder 44 is formed with an annular flange 45 engageable with the adapter 22. On one side of the flange 45 the cylinder lies within the adapter and supports a ring 46 Within which `the spindle bearing 3i is mounted. The other 42 and cylinder' 44 is a helical spring 48 interposed between -an annular shoulder 49 on the sleeve and a ring 5I surmounting the'cylinder andabutting against the flange 45. Thus. sleeve 42 is pressed by spring 43 forward relatively to kthe drill 34, and, in cooperation with sleeve extension 43, tends completely to enclose the drill. In the operation of the tool, the sleeve assembly limits against the work while the drill and tool body advance relatively thereto. The spring 4l thereby is placed under increased tension and presses the sleeve extension 43 into engagement with the work with increased intensity. During drilling, therefore, the extension 43 functions as a hold down portion of the sleeve, acting under the force of spring 48 to press the outer work sheet into firm engagement with the inner sheet. The hold down pressure is maintained throughout the drilling operation and until the point' of the drill is withdrawn from the Work and again surrounded by the sleeve extension.

The forward end of the sleeve 42 is reduced in diameter to receive the extension 43 which is adjustably secured therein in order that variations in drill length may be compensated for by varying the projecting length of the extension. The connection between the sleeve and extension thereof is effected through the engagement of complementary threaded portions thereon, while a lock nut 52 is provided for securing the extension in a set position of adjustment. Preferably the sleeve assembly normally occupies a position in which the work engaging end ofthe hold down portion 43 lies adjacent the point of the drill where it may contact the work immediately upon starting the drill hole. To this end forward movement of the assembly relative to the drill is limited by linkage conected at one end to the adapter 22 and at -the other end to the assembly, and operable to retract the assembly from normal working position. Included in this bent over ears on a bracket 56 which is fixed to the cylinder flange 45 by bolts 51. The lever 5l thus may be rocked about an yaxis transverse to the longitudinal axis of the drill. Below the trunnions 56 the lever 55 has an arm 55* extending -forwardly beneath the link 53 and shaped to nt 'within the palm of the operators hand to facilitate manual movement of th lever about its pivot. At its inner end the arm 55" has a tail portion 58 engageable with the bracket 56 to limit movement of the lever 55 and associated linkage in one direction. 'Ii'hrough the frictional contact between sleeve shoulder 54 and the neck of link 53 the control linkage is maintained normally in operative engagement with the sleeve. The pressure of spring 48 maintains the sleeve 42 in its maximum position of advancement which position is determined by the extent of rocking motion permitted the lever 55. Through the action of the spring and of the tail stop 58on lever Il the parts normally are held in the position shown in Figs. l and 4. To vretract the sleeve 42. to expose a greater portion of the pOint of the drill and f thereby facilitate its placement in a predetermined drilling position, tlie lever 55 may be rocked in a clockwise direction (Fig. 4) to move the link 53 rearward and thereby enforce a similar movement of the sleeve and extension 43 escasa: n

mem: (see-m. ),.m-f1inrn mia-ably is made ofspring steel toinsure against lzvi'uding,A

of the parts. y

1 As shown inFlg. 3 a, tool equipped with-the present attachment may be held and operated in the manner customary in the use of 'such tools. One hand is placed on thev handle 2l with the fingers in position to operate the trigger 2l, while the other hand grasps the tool forwardly of the handle in order to aid in rapid and accu- "rate'positioning of the drill point. In the present instance,l the elements of the hold down chip exhauster ar'e arranged to lie within` the grasp of the forwardly positioned hand. The actuating arm 55, by which movement of the attachment to advanced and retracted positions is controlled, may be held in the ngers or palm of the hand and operated without it being necessary for the operator to shift or otherwise change the position of his hands on the tool. When one drill hole is completed the tool is withdrawn from the work; the lever l5 is rocked, by a squeezing action', about its pivot to retract sleeve I2 and expose the point of the drill, which.' then is placed in a new drllling'position; the lever 55 is released, allowing spring Il to advance the sleeve assembly into engagement with the work; and the tool body pressed forward with a light pressure while the trigger 24 is actuated to start the motor and initiate drilling.

The chips of cut material and dust are carried to the interior ofthe sleeve l24 by the llutes of the drill, their progress being aided by the current of air entering the front of sleeve extensionl or hold down portion 43 and ilowing rearwardly around the drill through the bore 40. Inside the sleeve the chips and dust join the air current and are carried thereby through a peripheral opening 59 in the sleeve into a registering gooseneck 6l, to which the hose line 36 is connected, and thence to the dust bag 31, -Since it is the function ofthe attachment constantly to pick and exhaust the chips during' drilling and while the tool is being withdrawn from the drill hole, it is necessary to maintain the air stream in substantial volume while the front of sleeve extension 43 is pressed against the work. Therefore, as shown particularly in Figs. 9 and 10, the work engaging end of the hold down extension 43 is formed with a series di' radial grooves 62 open constantly for the passage of air tothe longitudinal bore B0. The air current thus originates immediately adjacent the drill hole and enforces the entrance of all dust particles into thesleeve,

:including those thrown from the drill by centrifugal force outward along the surface of the work.

The linkage for controlling advancement and retraction of the-sleeve assembly may be dispensed with without lmpairing the eillciency either of the hold down means orexhaust means of the attachment. A modiilcation of theV invention, in 4which the bell-crank lever 55 is omitted, is illustrated in Fig. ll. In this case a stop member or link replaces the corresponding element 53 of the first embodiment, the link 63 being mounted directly on the bracket 58 by a'lostl motion connection permitting a relative shifting movement of the link and sleeve assembly.4 The lost motion between the link and bracket is obtained through pin and slot connections 64, 85, one for each arm of the link. The modication oi Fig. 1l is mostadvantageously usedwith a Jigfwhich will guide the drill and render manual positioning thereof unn. Thillllt. one of which is shown kat iny Pig. 11. `isformcd `with a series of perforatlons t1 andA is adapted to be super-imposed on the outer work sheet with the perforation's therein aligned withthe. predetermined drilling positions. The diameter of each opening.v 61 is oi a sire onlytodmlt the sleeve extension 4I which isinsertedinaselectedopeningtobringthedrill point todrilling position. The sleeve extension engages and holds down the work as before, the attachment of this embodiment of the invention functioning in the same manner-,as thatrst describedA except that the sleeve'assembiy is not retracted betweenv the drilling operations.

What is claimed is:

l. In adrilling or like tool having a stationary support and a rotatable drill projecting therefrom, the combination of a sleeve mounted on said stationary support and encirclingv said drill, said sleevebeing shiftable to advanced and retracted positions relative to said drill to expose a lesser and greater portion of the outer end thereof, a yielding means urging said sleeve to advanced position, and means for moving said sleeve to retracted position and for controllin its movement to advanced position.

2. Al drilling or like tool according to claim l, characterized in that said last named means includes a stop defining the advanced position of said sleeve.

3. In a drilling or like tool having a stationary support and a rotatable drill projecting therefrom, the combination of a sleeve mounted on said support and encircling said drill, said sleeve being shiftable to advanced and retracted positions to expose a lesser and a greater portion of the outer end of the drill, a stop defining the advanced'position of said sleeve, and means for `moving said stop to retract said sleeve.

4. In a drilling or like tool having a stationary support and a rotatable drill projecting therefrom, the combination of a sleeve supported by said. support for reciprocable movement relative to said drill and surrounding said drill, a spring interposed between abutments on said sleeve and said support urging said sleeve outward relatively to said drill to engage and hold down the work, and means for retracting said sleeve against the pressure of said spring and for controlling the outward movement of said sleeve.

5.Y A drilling or like tool according to cla1m4, characterized in that said means comprises linkage connecting said ,sleeve and said stationary supportv acting to limit outward movement of said sleeve and .adapted for manual operation to retract said sleeve.

6. In a drilling or like tool having a stationary support and a rotatable drill projecting therefrom, an assembly for catching dust particles thrown from the drill by centrifugal. force outward along the surface of the work, comprising a sleeve lmounted on said stationary support for reciprocable movement relative to said drill and surrounding said drill, a. work engaging hold down portion closing the outer end of said sleeve and formed with va longitudinal bore permitting the passage of the drill therethrough and communicating the interior of the sleeve to atmosphere, a spring interposed between said sleeve and said support acting to press said sleeve in a) d irection to engage said hold down portion with the work, means for exhausting the interior oi said sleeve to generate a current of air flowing inward through saidhold down portion from the region of the drill hole, and a series of radial grooves formed in the outer endof said hold down portion, said grooves constituting constantly open air passages to which ilow streams of air over the the passage of the drill therethrough and movable V with said sleeve, means positively defining an advanced limit'of movement of the assembly comprising said sleeve and said hold down portion, yielding means urging said assembly to advanced position independently of said drill, and retraction means for said assembly comprising a manually operable lever mounted for oscillation about an axis transverse to the longitudinal axis of said drill and extending alongside'said sleeve in position to be encompassed therewith by the hand of the operator.

8. In a drilling or like too1 having a stationary support and a rotatable drill projecting therefrom, the combination of a tubular hold down attachment reciprocably mounted on said stationary support and surrounding said drill, yielding means urging said attachment outward independently of said drill whereby operation of the tool is accompanied by a pressure of said attachment against the work, and means for retracting said attachment from working position comprising manually operable linkage connected at one end to said stationary support and at the other end to said attachment and including an actuating lever extending alongside said sleeve in position y to be encompassed therewith by the hand of the operator.

9. In a drilling tool, an assembly forY catching dust particles thrown from the drill by centrifugal force outward along the surface of the work, comprising a tubular attachment adapted to be mounted on the front of the tool, and including a hold down portion surrounding the drill and engageable with the work during a drilling operation, means for generating a currentof air flowing'from the region of the drill point through said hold down portion to the interior of said attachment, and a plurality of radial grooves in the work engaging end of said hold down portion constituting constantly open air passages to which ow streams of air over` the surface of the work.

l0. An attachment for drilling and like tools, comprising a sleeve mounted on the front of the tool to encircle the drill and reciprocable relatively thereto, a helical spring surrounding said sleeve and based on said tool body urging said sleeve in a direction to engage it with the work, and a link intermediate said sleeve and the tool body having a neck portion adapted to embrace said sleeve and limit movement thereof by` said spring.

l1. An attachment for drilling and like tools, comprising a sleeve mounted on the front of the tool to encircle the drill and reciprocable relatool body having one arm connected to the link vasturiana tion, whereby to rock said lever and retract said link and thereby said sleeve.

l2. .An attachment for drilling and like tools, comprising a sleeve mounted on tle front of the tool to encircle the drill and reciprocable relatively thereto, means for controlling reciprocation of said sleeve including a link connected at its forward end to said sleeve and extending rearwardly toward the tool body, and a bell-crank lever pivotally mounted on the tool body having one arm connected to the rearward end of said link and the other armI arranged for manual operation.

13. In a drilling or like tool having a stationary support and a rotatable drill projecting therefrom, the combination of a work engaging hold down sleeve surrounding said drill and recip-' Jfor manual adjustment about its pivot to move said stop and thereby said sleeve in one direction and to control the movement thereof in the opposite direction. f-

14. A-portable drilling tool of the class which is held in forwardly4 ,and rearwardly positioned hands of the operator when in use, comprising a stationary housing adapted for the grasp of the rearwardly positioned hand of the operator, a rotatable drill projecting forwardly from said stationary housing, a tubular attachment surrounding said drill and supported bysaid housing for sliding movement longitudinally of said drill, said attachment being shiftable forward to engage and hold down the work While drilling and shiftable rearward to expose the point of the drill for ready positioning thereof in starting a new hole, and manually operable linkage disposed for the grasp of the forwardly positioned hand of the operator for shifting said attachment rearward and for controlling its movement forward.

15. A portable drilling tool of the class which is held in forwardly and rearwardly positioned hands of the operator when in use, comprising a stationary housing adapted for the grasp of the rearwardly positioned hand of the operator, Aa rotatable drill projecting forwardly from said stationary housing, a cylindrical housing extension surrounding said drill, a tubular attachment in telescopic connection with said extension and shiftable forward to engage and hold down the work while drilling and shiftable rearward to expose the point of the drill for ready positioning thereof in starting a new hole, a helical spring surrounding said extension and said attachment and urging said attachment forward, and means lWithin the grasp of the forwardly positioned hand of the operator for retracting said tubular attachment against the pressure of said spring.

16'. A portable drilling tool of the class which is held in forwardly and `rearwardly positioned hands of the operator when in use, comprising a stationary housing adapted for the grasp of the rearwardly positioned hand of the operator, a rotatable drill projecting forwardly from said stationary housing, a cylindrical housing extension surrounding said drill, a tubular attachment in telescopic connection with said extension vand shiftable forward to engage and hold down the work while drilling and shiftable rearward to expose the point of the drill for ready position- I and the other arm arranged for manual operaing thereof in starting a new hole, said attach- 16, characterized in that said means for controlling movement of said tubular attachment comprises a link connected at its forward end to the attachment and extending rearwardly toward the stationary housing, and a bell-crank lever pivotally mounted on said housing having one arm connected to said link and the'other arm arranged for manual operation as described.

HOWARD R. FISCHER. 

